Looking Up: Cassiopeia’s classic ‘W’ (or is it an ‘M’?)

Peter Becker More Content Now

Friday

Aug 16, 2019 at 9:49 AM

Cassiopeia the Queen is climbing high in the northeast on late August evenings. The constellation’s familiar “W” or “M” shape seems propped up on one side, eternally (by human standards) facing the North Star which is over to the left at this time. The five main stars of Cassiopeia are among the most recognized in the Northern Hemisphere’s night sky.

Cassiopeia is at its highest above the North Star in late August at about 2 a.m. The “W” has flipped upside down and looks like an “M.” About eight hours later (around 8 a.m., in daylight) the “M” has slipped down to the left of the North Star, with the “M” pointed to resemble a crudely scrawled letter “E.” To be able to see this in the dark of evening you will need to wait till winter.

In another eight hours, in late afternoon, Cassiopeia is at its lowest, below the North Star. The five stars now look like a “W” right side up.

This of course happens every day as the Earth spins and all the stars seems to revolve around the sky.

Here’s a little about the five main stars of Cassiopeia.

As seen in late August’s evening orientation, the white star at top is known as Caph, otherwise as Beta Cassiopeia. The slightly variable star has a mean brightness of +2.27 and is 54.5 light years away.

Next is Shedar, or Alpha Cassiopeia. This is an orange giant star, varying in magnitude, 2.20-2.23, and is around 228 light years from our Sun.

The center star of the “M” is Gamma Cassiopeia, which shifts from +2.20 magnitude to a dimmer +3.40. The blue star is approximately 610 light years away.

Next down is Ruchbah, or Delta Cassiopeia. Also variable, the star changes from 2.68 to 2.74 in a period of 460 days, due to a dimmer star passing in front of it in orbit. Ruchbah’s light takes 99 years to reach us.

The last star of the “M” is Segin, or Epsilon Cassiopeia. Shining steady at +3.34, this blue-white star is around 440 light years away.

Gamma Cassiopeia sadly lacks another name. Most prominent, naked-eye stars carry an ancient Arabic or Latin name. The star, however, was a major navigational beacon during the early space missions, and was nicknamed by the Mercury astronaut Vigil Ivan “Gus” Grissom as “Navi,” which was his middle name spelled backwards.

The classic “M” (or “W”) of Cassiopeia was thrown right off in 1572 when a brilliant star appeared close by. The powerful supernova was tracked by the famed Danish astronomer Tycho Brahe. It is often referred to as “Tycho’s Supernova.” The peak was on Nov. 16, when it was about magnitude -4 and visible in daylight. It was first seen in November 1572 and gradually faded from view in 1574. Its remnant dust cloud and X-rays are well known to modern astronomers.

There’s another brilliant star in Cassiopeia as well, but you can’t see it there from here.

You need to travel 4.3 light years to the Alpha Centauri star system, the closest star system to our own. Alpha Centauri is in the far southern sky, best seen from the Southern Hemisphere.

What is the name of the sixth bright star in Cassiopeia that you need to be at Alpha Centauri to see? The Sun.

Our Sun shines at magnitude +0.5 from Alpha Centauri or approximately the same as the bright star Vega, seen almost overhead on late-August evenings as seen from mid-northern latitudes. The Sun turns the “M” into a zig-zag from Alpha Centauri. Being only 4.3 light years further away, the other stars of the “M” would not be significantly dimmer.The Milky Way Band is visible on a dark night, among the stars of Cassiopeia. Scan the area with binoculars or a small telescope; there are several beautiful star clusters to see.

First quarter Moon is on Aug. 23.

Keep looking up!Peter Becker is Managing Editor at The News Eagle in Hawley, PA. Notes are welcome at news@neagle.com. Please mention in what newspaper or web site you read this column.

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